What is the best pressure to run in your mountain bike tires?
The right amount of pressure in your mountain bike tires will make an enormous difference in how the bike feels when you ride and not just that, but how it handles when you ride it.
The pressure in the tires of your bike needs to be quite precise so that it rides well for you.
The trick of it is, to know what the best pressure is because the rider, the tire and the bike will all combine to make the necessity different for each rider.

If your tire pressure is to high, you will ride higher, be less able to control your ride, both because there is less ground contact for your tire.
If the pressure is too low in your mountain bike tires, that will make your tires behave in an unpredictable way, so that it will seem to hop side to side, and will also make the bike get more pinch flats, which is a term used to mean when the tire actually gets pinched between the rim and whatever you just drove over, usually resulting in a flat.

Ground, terrain, type of bike, rider and other factors will determine what pressure is necessary but one way to learn that is to find a good tire pressure gauge and use it the entire time you’re making your tire pressure adjustments, that is to say, don’t switch out tools.
Start with a higher pressure toward the top end of what your tires say theyw ill handle, and try out the bike and how it feels.

Usually the larger a person you are, or the smaller the wheels of your mountain bike are, the larger amount of pressure you’re going to want to begin with.
Ride around with it, see how it feels and how the bike corners and feels on loose dirt or gravel.

Then lower that pressure by 5 pounds per square inch in both tires and try it again..
You will likely feel an improvement in how the bike grips the ground, but if you don’t, drop it another five pounds until you do.

What you’re attempting to do is get to the very lowest pressure you can ride on without having resistance from pinch flat type problems. Make sure that you don’t have that pinch flat resistance or you will end up with a flat, so keep your pressure up enough to prevent those.